The present invention relates to print control technique, and more particularly to a print control apparatus suitable for graphic printing with a small power in a dot printer.
In a prior art apparatus disclosed in JP-A-60-120072 (Canon), when the total number of data elements in a line to be printed is larger than a predetermined number, one line is scanned more than once so that the temperature rise of the print head is kept constant and the power consumption per unit time is kept constant. In another prior art apparatus disclosed in JP-A-60-21265 (Oki Electric), the degree of drop of the drive voltage of the print head or dot printing elements is monitored by an electric circuit, and if the print head drive voltage drops below a predetermined level as a result of high density printing, the print operation is stopped, and after the drive voltage has been restored, the print head is back-spaced to resume printing from the interrupted position.
In the former serial printer, means for counting the total number of dots in one line (for example, 2448.times.24 dots) is required, and if it is implemented by an electrical circuit, the amount of hardware increases. When the dot counter is implemented by a program, the processing time increases because the number of dots must be counted for each line and hence the throughput is reduced. In the latter printer, the method is effective when the size of one block is regularly predetermined such as Kanji or a specific graphic pattern having, for example, 24.times.24 dots per block. However, the halting and/or resumption of printing is permitted only block by block. As the technique has been developed recently, many apparatus support a graphic function including painting. In graphic printing, unlike character block printing with a constant interval between adjacent characters, since the size of the block cannot be uniformly determined, when printing is resumed after interruption, a gap or overlap is created at a position where the printing is interrupted due to a backlash of the print mechanism, a rise characteristic of the motor and a backlash of the ink ribbon feed mechanism. As a result, the print quality is lowered.